1. Field of the Invention
The present invention relates to a plastic molding which is applied to peripheries of a window panel or side faces of a body of an automobile for the purpose of decoration or protection of the vehicle body, and more precisely it relates to a plastic molding which presents a metallic color, such as stainless steel.
2. Description of Related Art
As a recent trend, front and rear window panels of an automobile are directly adhered to flanges of a body panel which define window openings. In this direct adhesion, a decorative plastic molding is provided to conceal a gap between the vehicle body panel and the window panel.
There are various known plastic moldings having metallic colors. In particular, a plastic molding presenting a metallic color of stainless steel is popularly used. Such a stainless steel color can be realized by applying a decorative film which is made of a plastic film metallized with a metal, such as chrome, onto the plastic substrate of the window molding, as disclosed for example in Japanese Examined Utility Model Publication (Kokoku) No. 61-2037.
The plastic molding disclosed in Kokoku No. 61-2037 has a decorative film which has improved weather-proofing and prevents wrinkling of the plastic molding which would otherwise occur when the plastic molding is bent along the profile of the window panel(s). The decorative film has an innermost layer of a vinyl chloride-vinyl acetate copolymer, an intermediate layer of ion cross-linking copolymer, and an outermost layer of fluoroplastics which is metallized at its internal surface with a chrome by vacuum evaporation on which the intermediate layer is superimposed. The decorative film is incorporated in a plastic molding of polyvinyl chloride, so that the outermost fluoroplastic layer is exposed.
The outermost fluoroplastic layer exhibits less aging and wrinkling when bent. However, the plastic molding mentioned above has the following drawback. Namely, usually, when the plastic molding is applied to the periphery of the window panel, it is subject to a cold bending. That is, the molding is successively bent and fixed along the profile of the gap between the vehicle body panel and the window panel at a normal temperature. However, when the molding after is applied to the vehicle, and experiences a change of ambient conditions, such as change of temperature due to direct sunlight, the inner side of the molding tends to wrinkle at the corner portions of window panels having large curvature. It has been experimentally confirmed by the inventors that the wrinkling was caused mainly by the separation of the metal layer from the ion cross-linking copolymer layer.
The inventors have conceived that the causes of the above-mentioned separation are that an unsaturated carboxylic acid of a base polymer of ion cross-linking copolymer is partly or entirely neutralized with a metal ion, resulting in a decreased adhesion of carboxylic acid to metal and that ion cross-linking can be easily dissociated by heat.